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FUNCTIONAL ROLES for POST-TRANSLATIONAL MODIFICATIONS of T-SNARES in PLATELETS

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FUNCTIONAL ROLES for POST-TRANSLATIONAL MODIFICATIONS of T-SNARES in PLATELETS University of Kentucky UKnowledge Theses and Dissertations--Molecular and Cellular Biochemistry Molecular and Cellular Biochemistry 2016 FUNCTIONAL ROLES FOR POST-TRANSLATIONAL MODIFICATIONS OF t-SNARES IN PLATELETS Jinchao Zhang University of Kentucky, [email protected] Digital Object Identifier: http://dx.doi.org/10.13023/ETD.2016.044 Right click to open a feedback form in a new tab to let us know how this document benefits ou.y Recommended Citation Zhang, Jinchao, "FUNCTIONAL ROLES FOR POST-TRANSLATIONAL MODIFICATIONS OF t-SNARES IN PLATELETS" (2016). Theses and Dissertations--Molecular and Cellular Biochemistry. 26. https://uknowledge.uky.edu/biochem_etds/26 This Doctoral Dissertation is brought to you for free and open access by the Molecular and Cellular Biochemistry at UKnowledge. It has been accepted for inclusion in Theses and Dissertations--Molecular and Cellular Biochemistry by an authorized administrator of UKnowledge. For more information, please contact [email protected]. STUDENT AGREEMENT: I represent that my thesis or dissertation and abstract are my original work. Proper attribution has been given to all outside sources. I understand that I am solely responsible for obtaining any needed copyright permissions. I have obtained needed written permission statement(s) from the owner(s) of each third-party copyrighted matter to be included in my work, allowing electronic distribution (if such use is not permitted by the fair use doctrine) which will be submitted to UKnowledge as Additional File. I hereby grant to The University of Kentucky and its agents the irrevocable, non-exclusive, and royalty-free license to archive and make accessible my work in whole or in part in all forms of media, now or hereafter known. I agree that the document mentioned above may be made available immediately for worldwide access unless an embargo applies. I retain all other ownership rights to the copyright of my work. I also retain the right to use in future works (such as articles or books) all or part of my work. I understand that I am free to register the copyright to my work. REVIEW, APPROVAL AND ACCEPTANCE The document mentioned above has been reviewed and accepted by the student’s advisor, on behalf of the advisory committee, and by the Director of Graduate Studies (DGS), on behalf of the program; we verify that this is the final, approved version of the student’s thesis including all changes required by the advisory committee. The undersigned agree to abide by the statements above. Jinchao Zhang, Student Dr. Sidney W. Whiteheart, Major Professor Dr. Michael D. Mendenhall, Director of Graduate Studies FUNCTIONAL ROLES FOR POST-TRANSLATIONAL MODIFICATIONS OF t-SNARES IN PLATELETS DISSERTATION A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the College of Medicine at the University of Kentucky By Jinchao Zhang Lexington, KY Director: Dr. Sidney W. Whiteheart, Professor of Molecular and Cellular Biochemistry Lexington, Kentucky 2016 Copyright © Jinchao Zhang 2016 ABSTRACT OF DISSERTATION FUNCTIONAL ROLES FOR POST-TRANSLATIONAL MODIFICATIONS OF t-SNARES IN PLATELETS Platelets affect vascular integrity by secreting a host of molecules that promote hemostasis and its sequela. Given its importance, it is critical to understand how platelet exocytosis is controlled. Post-translational modifications, such as phosphorylation and acylation, have been shown to affect signaling pathways and platelet function. In this dissertation, I focus on how these modifications affect the t-SNARE proteins, SNAP-23 and syntaxin-11, which are both required for platelet secretion. SNAP-23 is regulated by phosphorylation. Using a proteoliposome fusion assay, I demonstrate that purified IκB Kinase (IKK) phosphorylated SNAP-23, which increased the initial rates of SNARE-mediated liposome fusion. SNAP-23 mutants containing phosphomimetics showed enhanced initial fusion rates. These results, combined with previous work in vivo, confirm that SNAP-23 phosphorylation is involved in regulating membrane fusion, and that IKK-mediated signaling contributes to platelet exocytosis. To address the role(s) of acylation, I sought to determine how syntaxin-11 and SNAP-23 are associated with plasma membrane. Using metabolic labeling, I showed that both proteins contain thioester-linked acyl groups which turn over in resting cells. Mass spectrometry mapping showed that syntaxin-11 is modified on C275, 279, 280, 282, 283 and 285, while SNAP-23 is modified on C79, 80, 83, 85, and 87. To probe the effects of acylation, I measured ADP/ATP release from platelets treated with the acyl-transferase inhibitor, cerulenin, or the thioesterase inhibitor, palmostatin B. Cerulenin pretreatment inhibited t-SNARE acylation and platelet function while palmostatin B had no effect. Interestingly, pretreatment with palmostatin B blocked the inhibitory effects of cerulenin suggesting that maintaining the acylation state of platelet proteins is important for their function. Thus my work indicates that the enzymes controlling protein acylation could be valuable targets for modulating platelet exocytosis in vivo. KEYWORDS: Platelets, SNARE, Phosphorylation, Acylation, SNAP-23, Syntaxin-11 Jinchao Zhang April 7th, 2016 FUNCTIONAL ROLES FOR POST-TRANSLATIONAL MODIFICATIONS OF t-SNARES IN PLATELETS By Jinchao Zhang Dr. Sidney W. Whiteheart Director of Dissertation Dr. Michael D. Mendenhall Director of Graduate Studies April 7th, 2016 To Sheena, Raelene, Richard ACKNOWLEDGEMENTS I joined IBS program in 2009, and entered the Biochemistry Department in 2010. Time flies, but there are many great memories of my experiences. At the same time, there are a lot of people that I would like to acknowledge. I feel very blessed to have them in my graduate study. Firstly, I would like to express my deep gratitude to my mentor, Dr. Sidney “Wally” Whiteheart, he is the best mentor I have ever met, not only he is a great mentor in biomedical sciences, but also he is a role model in my life—work hard and be patient to others. During my graduate study, he is always training me to be a scientist with independent thinking and persistent hard working to accomplish the projects. In addition, he is also very patient when I met difficulties in my project. He is the mentor of precise and strict method, and requires his student to repeat experiments before concluding of the results. With all of that, I appreciate his kind mentoring and training during my graduate study. I would like to give my special acknowledgement to my committee members, Dr. Douglas Andres, Dr. Susan Smyth, Dr. Haining Zhu and their encouragement, advice, and technique support, which kept my research projects going smoothly. Without that, I would not think about my project so deeply. I would also appreciate that Dr. Andrew Morris is willing to be my outside examiner. During my research project, I am also thankful for his generosity in instruments and reagents provided for my liposome study. I would also like to thank Dr. Haining Zhu and Dr. Jing Chen in Dr. Zhu laboratory for mass spectrometry analysis during my acylation site study. iii I would like to thank previous lab colleagues. Especially, Dr. Michael C. Chicka and Dr. Qiansheng Ren both taught me how to design and carry out experiments and to analyze experimental problems during my IBS rotation in Dr. Whiteheart laboratory. I would like to give special thanks to Dr. Shaojing Ye and Dr. Yunjie Huang for their experiment assistance. I would thank Dr. Chunxia, Zhao, Dr. Rania Al. Hawas, Dr. Deepa Jonnalagadda, Dr. Elena A. Matveeva, Dr. Zubair A. Karim, Meenakshi Banerjee, and Smita Joshi in Dr. Whiteheart laboratory. I would like to specially thank Meenakshi Banerjee and Smita Joshi for their discussion and suggestion during our group meetings. Since I joined the Biochemistry Department, I have received numerous invaluable scientific training and help from the faculty, staff, and post-doc researchers. Firstly, I warmly thank Director of Graduate Studies (DGS), Dr. Michael Mendenhall and previous DGS Dr. Kevin Sarge for their kind support during my graduate study--helping and answering my questions when I needed their help. I will also give thanks to my student seminar advisors, Dr. Robert Dickson, Dr. Tianyan Gao, Dr. David Rodgers, Dr. Craig Vander Kooi and Dr. Haining Zhu. With their kind advice and patience, I improved my scientific presentation skill gradually. At the same time, I express my appreciation to Dr. Chunming Liu, Dr. Charles Waechter, Dr. Trevor Creamer, Dr. Rebecca Dutch and Dr. Peter Spielmann for their encouragement and generous reagents provided. In addition, I would like to give thanks to Dr. Jeffrey Rush, Dr. Martin Chow, Dr. Hanjun Guan, Dr. Carol Beach, Dr. Manana Melikishvili, Dr. Gabriel Popa, Dr. Xiaobo Li, Dr. Liuqing Yang and Erik Cook for their help in iv reagents and technique support. Also, I received a lot of love, help, care and encouragement from my friends, Ray, Jiawei, the Yip family, the Koh family and “uncle” Bill’s family. During these years of my graduate study, they always treated me as their family members whenever I met happiness or troubles. Their love and care encouraged me to finish my Ph.D study. Finally, I would like to give thanks to my families. My wife, who was willing to marry me, become the most important partner in my entire life. Whenever I failed or succeeded, she has always been standing on my side, without any hesitation. My daughter and son are the gifts from God and no matter the smile and cry remind me that I am a blessed dad and own an entire home through my life. My parents brought me up and always supported me with their love and care. My brother is my best friend in my entire life, and we share our happiness and sadness always. My parents in-law are the best in-laws and help us when we are busy with our work—sharing their love, taking care of kids and cooking for us.
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